We investigate dietary factors in cohort studies and nutrition related biomarkers in nested case controls studies within the PLCO screeening trial cohort. The dietary factors have included glycemic index and folate. Biomarkers studies have included vitamin D, and insulin like growth factors and insulin resistance factors. PLCO has also participated in the VDPP. Thus far the studies for vitamin D, the Vitamin D Pooling Project for Rare Cancers , the IGF-1 axis, TGF-B, leptin, and c-peptide biomarker studies, and the folate, glycemic index, fat dietary intake studies have completed and published.